Vessel occlusive devices are well known and commonly referred to as “artificial sphincters.” They are installed within the body to aid or replace the natural sphincter of the body. For example, men can become urinary incontinent for example following surgeries to remove cancerous prostates. Women can become incontinent for example due to the pelvic trauma caused during childbirth and due to a laxity of the pelvic muscles occurring due to aging. Further, men and women may be rendered incontinent due to for example trauma, infection and/or birth defects.
Urethral occlusive devices can be used to restore urinary continence to patients with urinary control problems caused by various neurological diseases, surgical procedures, spinal cord injury, etc. Other occlusive devices include those used for contracting the bowel to prevent fecal leakage, for contracting the esophagus to prevent gastro-esophageal reflux, or those used in the area of gastric banding for restricting the stomach in treatment for obesity, and occlusion of the seminal vesicles or fallopian tube to control male and/or female fertility, of which there are needs that exist for commercial devices that can be used in such applications.
In particular, devices utilizing hydraulic sphincters or cuffs described in U.S. Pat. Nos. 3,863,622; 4,222,377, 4,412,530 and 4,878,889, have been used to provide urethral occlusion. To use these types of devices, the patient squeezes a control pump, which transfers fluid from a cuff to a pressure regulating balloon. The balloon forces the fluid through a fluid restrictor and back into the cuff to reestablish an occlusive urethral pressure within 3-5 minutes. These urethral occlusive devices are complicated to implant. One problem with hydraulic sphincters or cuffs is that they often do not apply uniform pressure on the urethra. As the cuff or sphincter is inflated, it folds or changes its shape, often in a non-uniform manner, thereby exerting uneven occlusive force on the urethra. This can result in urinary leakage, urethral erosion, or the urethra tissue being worn away after extensive use.
In other examples, the American Medical Systems, Inc. AUS 800 is a totally implantable hydraulic sphincter implanted in both males and females experiencing urinary incontinence and has been on the market for more than 35 years. The AUS 800 and its predecessors are described in U.S. Pat. Nos. 3,863,622, 4,222,377, 4,412,530 and 4,878,889. The AUS 800 may have a silicone pressure regulating balloon implanted in the prevesical space, a silicone control pump implanted in the scrotum or labia and a silicone urethral occlusive cuff wrapped around the bulbous urethra in males or bladder neck in females. Each component may be filled with saline or radiopaque contrast media, and tubing emanating from each component may be routed between incisions for appropriate connections. The device can be deactivated for a period of approximately 6 weeks to allow tissue healing to proceed and urethral edema to subside. At activation, the control pump may be squeezed sharply to unseat a poppet and open operational fluid flow paths. The patient is taught to operate the device by squeezing the control pump through the scrotal or labial skin. This action can transfer fluid from the cuff to the pressure regulating balloon. The balloon can force the fluid through a fluid restrictor and back into cuff to reestablish an occlusive urethral pressure within 3-5 minutes. The AUS 800 can be complicated to implant and prone to fluid leakage, and may cause urethral atrophy and erosion. The complexity of its implantation is partly due to the requirement to intra-operatively fill and assemble its three components. The AUS 800 often fails due to wear in its componentry which leads to fluid leakage and post-operative infections. Urethral atrophy and erosion sometimes occur and are suspected to be due to the crenate shape of its occlusive cuff. Post-operative infection requiring explanation of the device also is a frequent complication. Despite these drawbacks, the AUS 800 is the only commercially available artificial urinary sphincter currently. The AUS 800 is available with a number of occlusive pressure ranges with 61-70 cm H2O being the pressure most frequently selected.
U.S. Pat. Nos. 5,704,893 and 6,074,341 discuss other types of urethral occlusive devices, which are entirely implantable artificial urinary sphincters. These artificial urinary sphincters are one-piece devices that do not require saline filling or intra-operative assembly, but where depression of a deactivation plunger, for example through the scrotal skin, causes a urethral occlusive sheath to expand and remove occlusive pressure from the urethra to allow normal urination. Depression of an activation button allows the occlusive sheath to contract and reapply urethral pressure to prevent urethral leakage. While such devices provided significant improvement in vessel occlusion, implantation in humans was impeded by growth of tough, fibrous tissue around the device, due to the natural defenses of the human body, which over time prevented expansion of the occlusive sheath.